1. Field of the Invention
The present invention relates to the production of oil in an oil well. More particularly, the present invention related to devices for preventing the movement of sand within the production tubing of an oil well.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
In many oil wells, in particularly those in fields that are established and aging, natural pressures decline to the point where the oil must be artificially lifted to the surface. Subsurface pumps are located down in the well below the level of the oil. A string sucker rod extends from the pump up to the surface to a pump jack device, or beam pump unit. A prime mover, such as a gasoline or diesel engine, or an electric motor, or a gas engine on the surface causes the pump jack to rock back and forth, thereby moving the string of sucker rods up and down inside the well tubing.
The string of sucker rods operates the subsurface pump. A typical pump has a plunger that is reciprocated inside of a barrel by the sucker rods. The barrel has a standing one-way valve, while the plunger has a traveling one-way valve, or in some pumps the plunger has a standing one-way valve, while the barrel has a traveling one-way valve. Reciprocation charges the chamber between the valves with fluid and then lifts the fluid up the tubing toward the surface.
During production of the formation fluid, mineral particles, often referred to as sand, may be swept into the flow path. The sand may erode production components, such as the downhole pump or sucker rod pump, the control valves on the surface, etc. in the flow path. When substantial quantities of sand are carried along as oil and/or gas is removed from a formation, the sand can eventually plug the openings into the interior of tubing by which the hydrocarbon production is withdrawn to the earth's surface. It is not uncommon for the pump itself to stick and/or the barrel to stick as a result of sand or other particulate matter becoming caught between the barrel and the plunger. The tolerances between the barrel and the plunger are close so as to effect a seal between the plunger and the barrel. If sand lodges therebetween, either the plunger or barrel will be cut or the plunger sticks in the barrel. The structure of such pumps makes them particularly prone to such damage because such pumps rely on a seal which is formed between the plunger and barrel by the leading edge of the plunger.
Generally, when the pump becomes “sanded in” in the production tubing, a very complicated procedure is required so as to remove the sanded-in components of the oil well. Typically, the production tubing would have to be removed so as to separate the pump from the tubing and to remove the sand accumulation. As such, it is important that sand be retained, as much as possible, in an area above the plunger and pump so as to prevent these problems from occurring.
In the past, various patents have issued relating to the prevention of sand movement in oil wells. For example, U.S. Pat. No. 3,106,526 issued on Oct. 8, 1963 to B. F. Schmidt, teaches a sand and gas deflector for oil well pumps. In particular, this patent describes an arrangement of baffles or deflectors attached to the production tubing which serve to guard against the entrance of sand from the well into the tubing through the inlet apertures.
U.S. Pat. No. 4,103,739, issued on Aug. 1, 1978 to L. D. Hall, teaches a sand release apparatus for a pump. There is provided a pair of telescoped tubular members threaded into the pump just above the lower end where sands locks the pump. The pair of telescoped tubular members are pinned by a shear pin. When it is time to pull the pump, if there is undue resistance to its removal from the tubing string, the shear pin will shear so as to release the tubular members for telescoping movement.
U.S. Pat. No. 5,141,411, issued on Aug. 25, 1992 to J. H. Klaeger, shows a fluid pump that is used stripper wells. The pump avoids sticking and sanding problems caused in such wells by routing fluid through an annulus between the plunger and the barrel and out of exit ports in order to flush particulate matter with each stroke of the plunger. As the plunger of the pump is reciprocated, the lower bearing surface of the valve member of the traveling valve contacts the upper bearing surface of the valve member of the standing valve when the plunger is near the maximum extent of downward travel to force the traveling valve open and/or force the standing valve closed depending on fluid pressure conditions and whether the standing valve is stuck open.
U.S. Pat. No. 5,295,537, issued on Mar. 22, 1994 to C. W. Trainer, discloses a sand-separating producing-well accessory. The separator causes fluid bearing particulate matter to be accelerated. This acceleration causes the particulate matter to separate from the fluid because of the higher mass and greater inertia of the particulate matter. The fluid, after separation of the particulate matter, is drawn up through the pump. The particulates accumulate within a sand trap which can be pulled from the well and emptied as desired. A strainer is added after the initial inertia separation of particles from the liquid.
U.S. Pat. No. 6,152,218, issued on Nov. 28, 2000 to M. R. Safargar, provides an apparatus for reducing production of particulate material in a well. The apparatus has tubular conduits having openings therein which are protected by flow diversion shields. The flow diversion shields are arranged so that the flow of the production fluids into the tubular conduit is less than the gravitationally-induced falling rate of the particulate matter. This separates a majority of the particulate material from the production fluid.
U.S. Pat. No. 6,273,690, issued on Aug. 14, 2001 to Fischer, Jr. et al., describes a downhole pump with bypass around the plunger. A bypass channel is provided between the barrel and the plunger so as to provide communication around the plunger and its one-way valve. The bypass channel is open when the reciprocal movement is near an end of the upstroke movement. When open, pressure across the plunger can equalize and gas inside the barrel chamber can vent around the plunger and/or pressure can equalize across the plunger one-way valve so as to prevent gas lock and minimize stress on the sucker rods.
U.S. Pat. No. 6,371,206, issued on Apr. 16, 2002 to R. J. Mills, discloses a method and apparatus for unblocking particulate plugs that develop, in a well. A valve is inserted in the production tubing above the pump in order to remove the plugs. The valve permits the well fluid to flow up past the valve but inhibits the well fluid from flowing down past the valve so that a majority of particles that settle from the well fluid when the pump is idle are trapped above the valve and do not plug the pump. A volume of well fluid trapped between the bottom of the valve and the top of the pump permits pressure waves induced by starting and stopping the pump to be generated. The pressure waves force fluids past the valve until the particles in the plug are resuspended so as to permit production to resume.
U.S. Pat. No. 6,619,390, issued on Sep. 16, 2003 to C. W. Kellett, teaches a particle separator for a fluid pump intake. This particle separator has a cylindrical body that is attachable to a pump by a flexible sleeve and has tangential slots directing intake fluid in a swirling manner about an inlet tube within the cylindrical body. The inlet has an enlarged outer diameter at its lower end which causes the swirling inlet fluid to accelerate in order to aid in particle separation.
U.S. Patent Publication No. 2010/0254839, published on Oct. 7, 2010 to K. Pulliam, describes a downhole sucker rod pump having a brush disposed between the downhole pump barrel and the well tubing to provide a seal which is not damaged during the insertion and/or withdrawal of the pump. The bush has a density and stiffness such that it provides a sufficient interference fit between the pump barrel and the well tubing.
It is an object of the present invention to provide a sealing apparatus that prevents sand and rust from collecting at the bottom of the annular space between the working barrel and the production tubing.
It is another object of the present invention to provide a sealing apparatus for an oil well in which minimizes the number of times that the pump has to be pulled for repair.
It is another object of the present invention to provide a sealing apparatus which prevents an accumulation of sand on the pump and which avoids the pump from becoming stuck.
It is another object of the present invention to provide a sealing apparatus for an oil well which allows hydrostatic pressures on opposite sides of the seal to equalize.
It is another object of the present invention to provide a sealing apparatus for an oil well which conforms to irregular shapes of production tubing.
It is another object of the present invention to provide a sealing apparatus for preventing sand
It is still a further object of the present invention to provide an apparatus for a pump of an oil well which is easy to install, relatively inexpensive and easy to manufacture.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.